Compositions containing hops extract and their use in water systems and process streams to control biological fouling

ABSTRACT

Biological fouling is effectively controlled in water systems and process streams through the addition of hops extract.

FIELD OF THE INVENTION

[0001] This invention relates generally to biocides and, moreparticularly, to compositions containing hops extract and their use inwater systems and process streams to control biological fouling.

BACKGROUND OF THE INVENTION

[0002] Growth of microorganisms such as bacteria, fungi and algae, aswell as macroorganisms such as mussels and clams, is problematic inwater systems and process streams. As used herein, “water systems” isdefined to include municipal, commercial and industrial water systems,as well as aqueous streams. The term “aqueous streams” includes, but isnot limited to, streams used for transporting or processing foodproducts and on food surfaces and equipment surfaces that come incontact with the aqueous stream. Examples of food products includefruits vegetables and tubers such as tomatoes, potatoes, bananas,apples, beets, and the like, and meats such as poultry, beef and thelike and the surfaces thereof. “Process streams,” as used hereinincludes, but is not limited to, sugar beet diffuser systems.

[0003] Proliferation of microorganisms and macroorganisms can causemechanical, operational and chemical problems with economic andhealth-related consequences. Similarly, growth of microorganisms inaqueous streams is undesirable. Poor biological control in these systemscan cause product spoilage and loss, high water use rates, and thepotential for health-related problems.

[0004] Many of the chemicals used to control biological fouling in watersystems and process streams were developed based on efficacy, withoutprimary emphasis on safety and environmental compatibility. Many ofthese chemicals are toxic to terrestrial animals or aquatic life, areeye or skin irritants, can produce sensitization reactions with repeatedexposure, or have toxic byproducts. There are many naturally-occurringsubstances with biocidal properties. Natural substances that controlmicrobial fouling have been, to some extent, optimized through evolutionand are, by definition, environmentally compatible. Product research anddevelopment guided by the use or imitation of natural microbial foulingcontrol substances has the potential to provide useful and innovativewater treatment chemistries.

[0005] Hops extract is typically produced as an amber colored liquidused primarily for flavor enhancement of beer. Hops extract is obtainedfrom the hop plant (Humulus lupulus) as a group of resins, commonlyreferred to as alpha acids, represented by humulone and its congeners(cohumulone, adhumulone) and beta acids, represented by lupulone and itscongeners (colupulone, adlupulone). Beta acid (lupulone) extracts fromhops are a product of the brewing process. Hops beta acid extracts arealso produced for use in the brewing process to alter properties of thefinished beverage. Therefore, abundant sources of raw material for hopsextract-based biological control products are available. The fact thathops extract alpha and beta acids are routinely consumed by humansemphasizes the favorable toxicity profile of these substances.

[0006] As known in the brewing industry, some hop acids haveantimicrobial activity against specific bacteria. For example, U.S. Pat.Nos. 5,082,975 and 5,166,449 disclose that the hop acidhexahydrolupulone inhibits the growth of certain Lactobacillus species.Similarly, U.S. Pat. No. 5,455,038 discloses the use oftetrahydroisohumulone or hexahydrocolupulone to inhibit the growth ofListeria species in food and food packaging materials; U.S. Pat. No.5,370,863 discloses the use of specific alpha and beta hop acids in oralcare compositions for inhibition of microorganisms that cause plaque andperiodontal disease; and U.S. Pat. No. 5,286,506 discloses the use ofhops extract beta acids to control pathogenic bacteria, such asListeria, in food.

[0007] In general, hops extract is a bacterial inhibitor, not abactericidal agent. Hops extract has poor efficacy against Gram-negativebacteria which are major slime-producing organisms in many watersystems. Hops extract is more effective against Gram-positive bacteria.For example, Leuconostoc mesenteroides is a significant problematicmicroorganism in sugar beet processing and diffuser systems and is aGram-positive organism which is susceptible to hops extract.Glutaraldehyde and other biocides are currently used in sugar beetdiffusion systems to control microbiological fouling due to Leuconostocand other bacteria. However, none of the biocides currently used in thisapplication, including glutaraldehyde, are as safe as hops extract. Theuse of hops extract in the sugar industry for microbial control has beenpreviously disclosed (Pollach, et al., Zuckerind. 121 (1996) Nr. 12, S.919-926; Hein et al., Zuckerind. 122 (1997) Nr. 12, S. 940-949; andPollach et al., Zuckerind. 124 (1999) Nr. 8, S. 622-637).

[0008] Growth of algae can be a problem in any water system exposed tosunlight. Uncontrolled algae growth typically begins as a cosmeticproblem, but can lead to problems such as distribution deck plugging andincreased halogen demand in cooling towers, and unacceptable waterquality in swimming pools, decorative fountain and other water features.Although there are numerous non-oxidizing biocides available for algaecontrol, many of these biocides have high human and environmentaltoxicity.

[0009] Chemistries found naturally or which mimic natural chemicalprocesses are commonly referred to as “green.” As environmentalrestrictions and regulations governing biocides increase, use of somebiocides may be restricted. Therefore, green biocides such hops extractmay provide an effective and environmentally sound biocide alternativein water treatment.

[0010] Accordingly, it would be desirable to provide a method ofcontrolling biological fouling in water systems and process streamsusing hops extract, a naturally-occurring biological control agent,which is safe and environmentally compatible.

[0011] It would also be desirable to provide novel biocidal compositionscontaining hops extract, in combination with other biocides.

[0012] It would futhermore be desirable to provide novel biocidalcompositions containing hops extract stabilized with surfactants toprevent hops extract product degradation, separation and precipitateformation prior to application. This surfactant-stabilized hops extractmay contain hops extract alone or in combination with other biocides.

SUMMARY OF THE INVENTION

[0013] The present invention calls for adding hops extract to a watersystem or process stream to control biological fouling. Hops extract canbe applied with greater safety, convenience and lower environmentalimpact than currently available biocides.

DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention is directed to a composition and method ofcontrolling biological fouling in water systems and process streams. Inaccordance with this invention, hops extract is added to the watersystem or process stream.

[0015] As used herein, “hops extract” is defined as extracts which areprimarily composed of beta acids, but which may also contain alphaacids. “Beta acids” are defined as lupulone, colupulone, adlupulone,hydrogenated lupulone, hydrogenated colupulone, hydrogenated adlupulone,mixtures thereof and the salts thereof. “Alpha acids” are defined ashumulone, cohumulone, adhumulone, hydrogenated humulone, hydrogenatedcohumulone, hydrogenated adhumulone, and the isomerized (cis- andtrans-) alpha acids, their congeners and their hydrogenated forms,mixtures thereof and the salts thereof.

[0016] The biological growth controlled by the method of the presentinvention may be microbiological or macrobiological in nature. As usedherein, “control” is defined to include inhibition, killing and removal.Microbiological growth includes bacteria, fungi, algae and combinationsthereof. Macrobiological growth includes, but is not limited to, zebramussels, blue mussels and the Asiatic clam.

[0017] The water systems to which hops extract may be added to controlbiological fouling include potable waters, cooling waters; food,beverage, and industrial process waters; pulp and paper mill systems;brewery pasteurizers; sweetwater systems; air washer systems; oil fielddrilling fluids and muds; petroleum recovery processes; industriallubricants; cutting fluids; heat transfer systems; gas scrubber systems;latex systems; clay and pigment systems; decorative fountains; waterintake pipes; ballast water tanks; and ship reservoirs, among others.

[0018] The hops extract is added to the water system or process streamby any conventional method at a concentration which effectively controlsbiological fouling. It is preferred that the amount of hops extract bein the range of about 0.01 ppm to about 10,000 ppm. More preferably, theamount of hops extract is from about 0.05 ppm to about 50 ppm, withabout 0.1 to about 10 ppm being most preferred.

[0019] Prior to its addition to the water system or process stream, thehops extract may optionally be stabilized with one or more surfactantssuch as dioctyl sodium sulfosuccinate, sodium mono- and dimethylnaphthalene sulfonates, N-lauroyl sarcosine sodium salt, alkylpolyglycoside and sodium dodecyl diphenyloxide disulfonate. Othersurfactant chemistries may also be used and are expected to similarlystabilize hops extracts. Some surfactants that are obvious choices foruse in stabilizing hops extract are those surfactants approved byregulatory agencies for indirect or direct food contact or for directaddition to food.

[0020] These surfactant and hops extract compositions are intended toillustrate the general invention that hops extracts can be stabilized byadding surfactants. This stabilization inhibits or prevents precipitateformation in the extract and preserves the integrity of the productprior to addition to the water system or process stream. Stabilizationof hops extract by use of this invention makes use of hops extract forbiological control possible in applications where large hops extractproduct volumes are required and where hops extract exposed to ambientenvironmental conditions is stored or used for biological control overextended periods of time.

[0021] One or more biocides may be added to the water system or processstream along with the hops extract to control biological fouling.Examples of suitable biocides include5-chloro-2-methyl-4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one,glutaraldehyde, 2,2-dibromo-3-nitrilopropionamide,2-bromo-2-nitropropane-1,3 diol, 1-bromo-1-(bromomethyl)-1,3propanedicarbonitrile, tetrachloroisophthalonitrile,alkyldimethylbenzylammonium chloride, dimethyl dialkyl ammoniumchloride,poly(oxyethylene(dimethyliminio)ethylene(diemethyliminio)ethylenedichloride, methylene bisthiocyanate, 2-decylthioethanamine,tetrakishydroxymethyl phosphonium sulfate, dithiocarbamate,cyanodithioimidocarbonate, 2-methyl-5-nitroimidazole-1-ethanol,2-(2-bromo-2-nitroethenyl)furan, beta-bromo-beta-nitrostyrene,beta-nitrostyrene, beta-nitrovinyl furan, 2-bromo-2-bromomethylglutaronitrile, bis(trichloromethyl) sulfone,S-(2-hydroxypropyl)thiomethanesulfonate,tetrahydro-3,5-dimethyl-2H-1,3,5-hydrazine-2-thione,2-(thiocyanomethylthio)benzothiazole, 2-bromo-4′-hydroxyacetophenone,1,4-bis(bromoacetoxy)-2-butene, bis(tributyltin)oxide, copper sulfate,(2-tert-butylamino)-4-chloro-6-(ethylamino)-s-triazine, dodecylguanidineacetate, dodecylguanidine hydrochloride, coco alkyldimethylamine oxide,n-coco alkyltrimethylenediamine, tetra-alkyl phosphonium chloride,7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylic acid,2-(4-thiazolyl)-benzimidazole, orthophenylphenol,6-ethoxy-1,2-dihydro-2,2,4-trimethyl quinoline and4,5-dichloro-2-n-octyl-4-isothiazoline-3-one.

[0022] The biocides may be added to the water system or process streamby any conventional method. It is preferred that the amount of biocidebe in the range of about 0.01 ppm to about 10,000 ppm. More preferably,the amount of biocide is from about 0.05 ppm to about 50 ppm, with about0.1 ppm to about 10 ppm being most preferred.

[0023] The use of hops extract and another biocide in combinationsurprisingly leads to unexpectedly superior results and allows forsignificantly less use when utilized in combination, as compared to theamount of each needed individually to achieve the same biocidalperformance. This biocidal synergy of the combined hops extract andbiocide can be achieved by adding hops extract and a biocide to thewater system or process stream simultaneously from individual containersor by applying a single composition that contains both hops extract andbiocide.

[0024] The present invention provides superior biological foulingcontrol when a composition is added to the water system, or processstream which contains hops extract and at least one biocide selectedfrom the group consisting of 5-chloro-2-methyl-4-isothiazolin-3-one,2-methyl-4-isothiazolin-3-one, glutaraldehyde,2,2-dibromo-3-nitrilopropionamide, 2-bromo-2-nitropropane-1,3 diol,1-bromo-1-(bromomethyl)-1,3-propanedicarbonitrile,tetrachloroisophthalonitrile, alkyldimethylbenzylammonium chloride,dimethyl dialkyl ammonium chloride,poly(oxyethylene(dimethyliminio)ethylene(diemethyliminio)ethylenedichloride, methylene bisthiocyanate, 2-decylthioethanamine,tetrakishydroxymethyl phosphonium sulfate, dithiocarbamate,cyanodithioimidocarbonate, 2-methyl-5-nitroimidazole-1-ethanol,2-(2-bromo-2-nitroethenyl)furan, beta-bromo-beta-nitrostyrene,beta-nitrostyrene, beta-nitrovinyl furan, 2-bromo-2-bromomethylglutaronitrile, bis(trichloromethyl) sulfone,S-(2-hydroxypropyl)thiomethanesulfonate,tetrahydro-3,5-dimethyl-2H-1,3,5-hydrazine-2-thione,2-(thiocyanomethylthio)benzothiazole, 2-bromo-4′-hydroxyacetophenone,1,4-bis(bromoacetoxy)-2-butene, bis(tributyltin)oxide, copper sulfate,(2-tert-butylamino)-4-chloro-6-(ethylamino)-s-triazine, dodecylguanidineacetate, dodecylguanidine hydrochloride, coco alkyldimethylamine oxide,n-coco alkyltrimethylenediamine, tetra-alkyl phosphonium chloride,7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylic acid,2-(4-thiazolyl)-benzimidazole, orthophenylphenol,6-ethoxy-1,2-dihydro-2,2,4-trimethyl quinoline and4,5-dichloro-2-n-octyl-4-isothiazoline-3-one.

[0025] It is preferred that the amount of hops extract in thecomposition be in the range of about 0.1% to about 99% and the amount ofbiocide be in the range of about 0.1% to about 99%.

[0026] The hops extract in the synergistic hops extract/biocidecomposition may also be stabilized with one or more surfactants toprevent the precipitation of the beta acids over time. Suitablesurfactants include, but are not limited to, dioctyl sodiumsulfosuccinate, sodium mono- and dimethyl naphthalene sulfonates,N-lauroyl sarcosine sodium salt, alkyl polyglycoside and sodium dodecyldiphenyloxide disulfonate. Other surfactant chemistries may also be usedand are expected to similarly stabilize hops extracts. Some surfactantsthat are obvious choices for use in stabilizing hops extract are thosesurfactants approved by regulatory agencies for indirect or direct foodcontact or for direct addition to food.

[0027] It is preferred that the amount of hops extract in thecomposition be in the range of about 0.1% to about 99%, the amount ofbiocide be in the range of about 0.1% to about 99% and the amount ofsurfactant be in the range of about 0.1% to about 99%.

[0028] The present inventors have surprisingly discovered thatbiological fouling can be effectively controlled in water systems andprocess streams through the addition of hops extract. In addition, hopsextract can be applied with greater safety, convenience and lowerenvironmental impact than currently available biocides. Moreover, thepresent invention improves on current technology by demonstratingsynergy between hops extract and a wide variety of other biocides. Hopsextract and biocides may be used in synergistic combinations to yieldbetter biocidal performance than when hops extract or the biocides areused individually. Hops extract and each biocide may act on targetorganisms in different ways to cause cell growth inhibition or death. Inaddition, using a combination of hops extract and one or more biocidesallows for application of less total hops extract and/or biocide toachieve a desired level of control. This has safety, environmental andeconomic advantages. It allows for reduced discharge of potentialpollutants, safer application and a more cost effective biologicalcontrol program.

[0029] Safety, as well as low human and environmental toxicities, aresome of the primary advantages of the inventive compositions compared topreviously described compositions used to control biological fouling. Inaddition to these primary advantages, the inventive compositions haveother benefits such as low volatility and lack of malodors.

[0030] Furthermore, this invention provides algicidal and algistaticactivities of hops extracts alone and in synergistic compositions withother biocides. The activity of hops extract against algae has not beendescribed previously and was surprising. These compositions arepotentially useful in controlling algae in a wide variety of watersystems exposed to sunlight and in controlling other organisms that growin water systems and process streams.

EXAMPLES

[0031] The following examples are intended to be illustrative of thepresent invention and to teach one of ordinary skill how to make and usethe invention. These examples are not intended to limit the invention orits protection in any way.

Example 1

[0032]Chlorella sorokiniana and Scenedesmus obliquus green algae weregrown separately in proteose medium (pH 6.8), harvested bycentrifugation and resuspended in proteose medium to concentrate cells.Algae cells were added to 20 ml sterile proteose medium in ten 50 mlPYREX® flasks. Each flask contained a different dilution of hopsextract. The hops extract used for these experiments was a ten percentaqueous solution of beta acids. Hops extract concentration in all of theexamples is expressed as ppm (beta acids). The number of algae colonyforming units per milliliter (CFU/ml) at time zero was determined byplate counts on proteose medium agar plates. The algal population (inCFU/ml) at time zero was 6×10⁵ for the Chlorella sorokiniana and 3×10⁴for the Scenedesmus obliquus. Algae cultures were incubated at 25° C.without shaking under grow lights with 16 hour/8 hour light/dark cycles(cool-white fluorescent lamps, 1255 lux) for 14 days. Followingincubation, the optical density (OD) at 750 nm (GBC Cintra 5spectrophotometer, 1 cm light path) and/or adenosine triphosphate (ATP)levels [Nalco TRA-CIDE® method, reported as Relative Light Units (RLU)]of each culture were measured. As shown below in Tables 1 and 2, hopsextract beta acids exhibited the ability to inhibit algae growth. TABLE1 Inhibition of Chlorella sorokiniana growth Beta acids (ppm) Culture OD750 nm Percent Inhibition of Growth  0 0.248 —  1 0.220 11  2 0.233  6 4 0.222 10  8 0.193 22 16 0.158 36 32 0.119 52 64 0.065 74 128  0.02192

[0033] TABLE 2 Inhibition of Scenedesmus obliquus Percent PercentInhibition Beta acids Culture OD Inhibition of ATP of ATP ppm 750 nmGrowth (RLU) Production  0 0.137 — 44430 —  1 0.103 25 38556 13  2 0.10523 31892 28  4 0.109 20 32893 26  8 0.047 66 18354 59 16 0.002 99  111297 32 0.002 99  882 98 64 0.004 97  802 98

Example 2

[0034] 100 ul pure culture algae (Chlorella sorokiniana or Scenedesmusobliquus green algae at 10⁷ CFU/ml) in synthetic cooling water (pH 8.2)were added to 200 ul hops extract dilutions in synthetic cooling waterin microplate (FALCON® 3075) wells. Microplates were covered with theprovided and incubated at 25° C. for six days with 16 hour/8 hourlight/dark cycles (cool-white fluorescent lamps, 1255 lux). Followingincubation, supernatant was removed from each microplate well by vacuumaspiration. Algae cells remained attached to the bottom of each well.200 ul of dimethylsulfoxide (DMSO) were added to each microplate well todissolve algae cells and extract chlorophyll. The optical density at 650nm of each extraction was determined by a microplate reader. (BeckmanBiomek®). The optical density (absorbance at 650 nm) of each extractioncorrelated with the amount of chlorophyll in each algal aliquotfollowing incubation with hops extract. Decreased chlorophyll indicatesalgicidal activity. As shown below in Table 3, hops extract exhibitedthe ability to kill algae. TABLE 3 Algicidal activity against Chlorellasorokiniana and Scenedesmus obliquus Ppm beta acids Chlorellasorokiniana Scenedesmus obliquus  0 0.48 0.52  4 0.46 (4) 0.50 (4)  80.45 (6) 0.47 (10) 16 0.43 (10) 0.40 (23) 32 0.39 (19) 0.21 (60) 64 0.18(63) 0.17 (67) 128  0.08 (83) 0.13 (75) 256  0.06 (88) 0.12 (77)

Example 3

[0035] Synergism refers to a case in which the performance of two ormore active ingredients is improved relative to the sum of theirindividual performances. The accepted method used to determine synergismis described by Kull, F. C., Eisman, P. C., Sylwestrowicz, H. D., andMayer, R. L. in Applied Microbiology 9:538-541 (1961), and is well knownin the art.

[0036] The equation for determining synergism is as follows:

Q _(a) /Q _(A) +Q _(b) /Q _(B)=Synergism Index (SI)

[0037] Where Q_(A) and Q_(B) are the concentrations of compounds A or Bthat produce an endpoint when acting alone, and where Q_(a) and Q_(b)are the concentrations of compounds A or B acting in the A/B combinationrequired to produce an endpoint. The endpoint is defined by theparticular test method, for example, an optical density.

[0038] To determine synergism, one evaluates the Synergism Index (SI).Where SI is less than 1, the performance of the mixture is superior tothe sum of the individual performances and synergism exists.

[0039] The efficacy of the invention was tested in the following manner:

[0040]Scenedesmus obliquus green algae cells were prepared in syntheticcooling water (pH 8.2) to a concentration of 10⁷ CFU/ml. 100 ul of thealgae suspension were added to 200 ul aliquots of hops extractantimicrobial compositions in synthetic cooling water contained in 96well microplates (FALCON® 3075). A wide range of hops extract/biocidecombinations were tested. Microplates were covered with the provided lidand incubated at 25° C. for six days with 16 hour/8 hour light/darkcycles (cool-white fluorescent lamps, 1255 lux). Following incubation,supernatant was removed from each microplate well by vacuum aspiration.Algae cells remained attached to the bottom of each microplate well. 200ul of dimethylsulfoxide (DMSO) were added to each microplate well todissolve the algae cells and extract chlorophyll. The optical density at650 nm of each extraction was determined using a plate reader (BeckmanBiomek®). The optical density of each extraction correlated with theamount of chlorophyll in each algae aliquot following incubation withhops extract compositions.

[0041] Synergistic compositions were made by mixing hops extract witheach of the following compounds: methylchloro/isothiazolone (“IZN”),poly(oxyethylene(dimethyliminio)ethylene(dimethyliminio)ethylenedichloride) (“POLYQUAT”), glutaraldehyde (“GLUT”),2-(tert-butylamino)4-chloro-6(ethylamino)-s-triazine (“TBTZ”),4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOI),tetrakishydroxymethyl phosphonium sulfate (“THPS”),2-(2-bromo-2-nitroethenyl)furan (“BNEF”),2,2-dibromo-3-nitilopropionamide (“DBNPA”), and 2-(decylthio)ethanamine(“DTEA”) in water at room temperature. A wide range of ratios of the twoactive ingredients can be used, depending on several factors includingthe microorganisms to be controlled. In this example, data designated asQ_(A) and Q_(a) in each case are for hops extract and data designated asQ_(B) and Q_(b) are for the other antimicrobial (IZN, POLYQUAT, GLUT,TBTZ, DCOI, THPS, BNEF, DBNPA, and DTEA).

[0042] Table 4 illustrates synergistic combinations of hops extract withother antimicrobials. A wide range of combinations were testedsystematically until synergistic compositions were discovered. Theantimicrobial compositions shown below exhibit synergistic activity withrespect to green algae. However, the examples disclosed herein shouldnot be considered to disclose all possible microorganisms which may becontrolled by the synergistic combinations, nor should the identifiedranges be viewed as limiting in nature. All synergistic antimicrobialcombinations of the identified ingredients are intended to be within thescope of the present invention, and all antimicrobial uses thereof areintended to be claimed. TABLE 4 Antimicrobial Q_(A) Q_(B) Q_(a) Q_(b) SIQ_(a):Q_(b) IZN² >256 (512)¹ >16 (32) 256 8 0.75 32:1  128 8 0.50 16:1 64 8 0.38 8:1 128 16 0.75 8:1 64 16 0.63 4:1 32 16 0.56 2:1 16 16 0.531:1 POLYQUAT³ 256 >16 (32) 64 4 0.38 16:1  128 8 0.75 16:1  64 8 0.508:1 GLUT⁴ 32 >16 (32) 16 4 0.63 4:1 TBTZ⁵ 32 16 16 0.5 0.53 8:1 16 40.75 4:1 DCOI⁶ 256 >16 (32) 128 0.5 0.52 256:1  128 1 0.53 128:1  128 20.56 64:1  128 4 0.63 32:1  128 8 0.75 16:1  64 8 0.50 8:1 64 16 0.754:1 4 16 0.52 1:4 THPS⁷ 32 16 8 4 0.50 2:1 4 4 0.38 1:1 8 8 0.75 1:1BNEF⁸ 32 >16 (32) 16 1 0.53 16:1  8 16 0.75 1:2 4 16 0.63 1:4 DBNPA⁹64 >16 (32) 16 16 0.75 1:1 4 16 0.56 1:4 DTEA¹⁰ 32 16 16 1 0.56 16:1  162 0.63 8:1 4 2 0.25 2:1 8 4 0.50 2:1 8 8 0.75 1:1 4 8 0.63 1:2

Example 4

[0043] When packaging hops extract, a container is filled with theproduct and sealed immediately, or it may be packaged in an atmosphere,such as nitrogen, other than the ambient air environment. Upon openingsuch a product container and exposing to ambient air, precipitateformation within the hops extract product is frequently observed withina few days. All of the product in the container must be used prior toprecipitate formation. If product is not used prior to this time, hopsextract quality and effectiveness are compromised and the product may berendered useless. Additionally, the container itself may be damaged dueto collection of insoluble hops extract precipitates and the containermay be rendered useless. Table 5 illustrates newly invented compositionscontaining hops extract and surfactants in which precipitate formationwas inhibited. Freshly prepared hops beta acid extracts were placed intubes (Coming® modified polystyrene 15 milliliter sterile centrifugetubes with caps), to which surfactants were added to the desiredconcentration (5 milliliter total volume). Tubes were stored unsealed atroom temperature in the dark for 72 hours. Following this period, theproduct in each tube was examined visually for precipitate formation.For each hops extract and surfactant composition, a critical level ofsurfactant was required to inhibit precipitate formation. TABLE 5Surfactant Active Hops Extract Ingredient Final Beta Acid PrecipitateConcentration Concentration Formation Surfactant (percent) (percent)(Yes, Slight, No) control  0 12.0 Yes OSS 10 10.3 No OSS  5 11.1 No OSS 1 11.8 Yes MNS 10  6.0 No MNS  5  9.0 Slight MNS  1 11.4 Yes NLS 10 6.0 No NLS  5  9.0 No NLS  1 11.4 Yes

[0044] In addition to the hops extract/surfactant compositions describedabove, hops extract compositions were also stabilized using alkylpolyglycoside and sodium dodecyl diphenyloxide disulfonate. Compositionscontaining 25 percent alkyl polyglycoside or sodium dodecyldiphenyloxide disulfonate and six percent beta acids were stable (noprecipitate formation observed) for >80 days. Without the surfactantaddition, the same hops extract beta acid preparations formedprecipitate within 48 hours.

[0045] While the present invention is described above in connection withpreferred or illustrative embodiments, these embodiments are notintended to be exhaustive or limiting of the invention. Rather, theinvention is intended to cover all alternatives, modifications andequivalents included within its spirit and scope, as defined by theappended claims.

What is claimed is:
 1. A method of controlling biological fouling in water systems and process streams comprising the step of adding thereto an effective amount of hops extract.
 2. The method of claim 1 wherein the hops extract is added to the water system or process stream in an amount from about 0.01 ppm to about 10,000 ppm.
 3. The method of claim 1 wherein the hops extract is added to the water system or process stream in an amount from about 0.05 ppm to about 50 ppm.
 4. The method of claim 1 wherein the hops extract is added to the water system or process stream in an amount from about 0.1 ppm to about 10 ppm.
 5. The method of claim 1 wherein the hops extract is stabilized with at least one surfactant prior to addition.
 6. The method of claim 5 wherein the surfactant is selected from the group consisting of dioctyl sodium sulfosuccinate, sodium mono- and dimethyl napthalene sulfonates, N-lauroyl sarcosine sodium salt, alkyl polyglycoside and sodium dodecyl diphenyloxide disulfonate.
 7. The method of claim 1 wherein an effective amount of at least one biocide is added to the water system or process stream.
 8. The method of claim 7 wherein the biocide is selected from the group consisting of 5-chloro-2-methyl-4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, glutaraldehyde, 2,2-dibromo-3-itrilopropionamide, 2-bromo-2-nitropropane-1,3 diol, 1-bromo-1-(bromomethyl)-1,3-propanedicarbonitrile, etrachloroisophthalonitrile, alkyldimethylbenzylammonium chloride, dimethyl dialkyl ammonium chloride, poly(oxyethylene(dimethyliminio)ethylene(diemethyliminio)ethylene dichloride, methylene bisthiocyanate, 2-decylthioethanamine, tetrakishydroxymethyl phosphonium sulfate, dithiocarbamate, yanodithioimidocarbonate, 2-methyl-5-nitroimidazole-1-ethanol, 2-(2-bromo-2-nitroethenyl)furan, beta-bromo-beta-nitrostyrene, beta-nitrostyrene, beta-nitrovinyl furan, 2-bromo-2-bromomethyl glutaronitrile, bis(trichloromethyl) sulfone, S-(2-hydroxypropyl)thiomethanesulfonate, tetrahydro-3,5-dimethyl-2H-1,3,5-hydrazine-2-thione, 2-(thiocyanomethylthio)benzothiazole, 2-bromo-4′-hydroxyacetophenone, 1,4-bis(bromoacetoxy)-2-butene, bis(tributyltin)oxide, copper sulfate, (2-tert-butylamino)-4-chloro-6-(ethylamino)-s-triazine, dodecylguanidine acetate, dodecylguanidine hydrochloride, coco alkyldimethylamine oxide, n-coco alkyltrimethylenediamine, tetra-alkyl phosphonium chloride, 7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylic acid, 2-(4-thiazolyl)-benzimidazole, orthophenylphenol, 6-ethoxy-1,2-dihydro-2,2,4-trimethyl quinoline and 4,5-dichloro-2-n-octyl-4-isothiazoline-3-one.
 9. The method of claim 7 wherein the biocide is added to the water system or process stream in an amount from about 0.01 ppm to about 10,000 ppm.
 10. The method of claim 7 wherein the biocide is added to the water system or process stream in an amount from about 0.05 ppm to about 50 ppm.
 11. The method of claim 7 wherein the biocide is added to the water system or process stream in an amount from about 0.1 ppm to about 10 ppm.
 12. A method of controlling biological fouling in water systems and process streams comprising the step of adding thereto an effective amount of stabilized hops extract.
 13. The method of claim 12 wherein the hops extract is stabilized with at least one surfactant
 14. The method of claim 13 wherein the surfactant is selected from the group consisting of dioctyl sodium sulfosuccinate, sodium mono- and dimethyl napthalene sulfonates, N-lauroyl sarcosine sodium salt, alkyl polyglycoside and sodium dodecyl diphenyloxide disulfonate.
 15. The method of claim 12 wherein the stabilized hops extract is added to the water system or process stream in an amount from about 0.01 ppm to about 10,000 ppm.
 16. The method of claim 12 wherein the stabilized hops extract is added to the water system or process stream in an amount from about 0.05 ppm to about 50 ppm.
 17. The method of claim 12 wherein the stabilized hops extract is added to the water system or process stream in an amount from about 0.1 ppm to about 10 ppm.
 18. The method of claim 12 wherein an effective amount of at least one biocide is added to the water system or process stream.
 19. The method of claim 18 wherein the biocide is selected from the group consisting of 5-chloro-2-methyl-4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, glutaraldehyde, 2,2-dibromo-3-nitrilopropionamide, 2-bromo-2-nitropropane-1,3 diol, 1-bromo-1-(bromomethyl)-1,3-propanedicarbonitrile, tetrachloroisophthalonitrile, alkyldimethylbenzylammonium chloride, dimethyl dialkyl ammonium chloride, poly(oxyethylene(dimethyliminio)ethylene(diemethyliminio)ethylene dichloride, methylene bisthiocyanate, 2-decylthioethanamine, tetrakishydroxymethyl phosphonium sulfate, dithiocarbamate, cyanodithioimidocarbonate, 2-methyl-5-nitroimidazole-1-ethanol, 2-(2-bromo-2-nitroethenyl)furan, beta-bromo-beta-nitrostyrene, beta-nitrostyrene, beta-nitrovinyl furan, 2-bromo-2-bromomethyl glutaronitrile, bis(trichloromethyl) sulfone, S-(2-hydroxypropyl)thiomethanesulfonate, tetrahydro-3,5-dimethyl-2H-1,3,5-hydrazine-2-thione, 2-(thiocyanomethylthio)benzothiazole, 2-bromo-4′-hydroxyacetophenone, 1,4-bis(bromoacetoxy)-2-butene, bis(tributyltin)oxide, copper sulfate, (2-tert-butylamino)-4-chloro-6-(ethylamino)-s-triazine, dodecylguanidine acetate, dodecylguanidine hydrochloride, coco alkyldimethylamine oxide, n-coco alkyltrimethylenediamine, tetra-alkyl phosphonium chloride, 7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylic acid, 2-(4-thiazolyl)-benzimidazole, orthophenylphenol, 6-ethoxy-1,2-dihydro-2,2,4-trimethyl quinoline and 4,5-dichloro-2-n-octyl-4-isothiazoline-3-one.
 20. The method of claim 18 wherein the biocide is added to the water system or process stream in an amount from about 0.01 ppm to about 10,000 ppm.
 21. The method of claim 18 wherein the biocide is added to the water system or process stream in an amount from about 0.05 ppm to about 50 ppm.
 22. The method of claim 18 wherein the biocide is added to the water system or process stream in an amount from about 0.1 ppm to about 10 ppm.
 23. A composition for controlling biological fouling in water systems and process streams which comprises an effective amount of hops extract and at least one biocide selected from the group consisting of 5-chloro-2-methyl-4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, glutaraldehyde, 2,2-dibromo-3-nitrilopropionamide, 2-bromo-2-nitropropane-1,3 diol, 1-bromo-1-(bromomethyl)-1,3-propanedicarbonitrile, tetrachloroisophthalonitrile, alkyldimethylbenzylammonium chloride, dimethyl dialkyl ammonium chloride, poly(oxyethylene(dimethyliminio)ethylene(diemethyliminio)ethylene dichloride, methylene bisthiocyanate, 2-decylthioethanamine, tetrakishydroxymethyl phosphonium sulfate, dithiocarbamate, cyanodithioimidocarbonate, 2-methyl-5-nitroimidazole-1-ethanol, 2-(2-bromo-2-nitroethenyl)furan, beta-bromo-beta-nitrostyrene, beta-nitrostyrene, beta-nitrovinyl furan, 2-bromo-2-bromomethyl glutaronitrile, bis(trichloromethyl) sulfone, S-(2-hydroxypropyl)thiomethanesulfonate, tetrahydro-3,5-dimethyl-2H-1,3,5-hydrazine-2-thione, 2-(thiocyanomethylthio)benzothiazole, 2-bromo-4′-hydroxyacetophenone, 1,4-bis(bromoacetoxy)-2-butene, bis(tributyltin)oxide, copper sulfate, (2-tert-butylamino)-4-chloro-6-(ethylamino)-s-triazine, dodecylguanidine acetate, dodecylguanidine hydrochloride, coco alkyldimethylamine oxide, n-coco alkyltrimethylenediamine, tetra-alkyl phosphonium chloride, 7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylic acid, 2-(4-thiazolyl)-benzimidazole, orthophenylphenol, 6-ethoxy-1,2-dihydro-2,2,4-trimethyl quinoline and 4,5-dichloro-2-n-octyl-4-isothiazoline-3-one.
 24. The composition of claim 23 wherein the amount of hops extract is in the range of about 0.1% to about 99% and the amount of biocide is in the range of about 0.1% to about 99%.
 25. A composition for controlling biological fouling in water systems and process streams which comprises an effective amount of stabilized hops extract.
 26. The composition of claim 25 wherein the hops extract is stabilized with at least one surfactant.
 27. The composition of claim 26 wherein the surfactant is selected from the group consisting of dioctyl sodium sulfosuccinate, sodium mono- and dimethyl napthalene sulfonates, N-lauroyl sarcosine sodium salt, alkyl polyglycoside and sodium dodecyl diphenyloxide disulfonate.
 28. The composition of claim 25 further comprising an effective amount of at least one biocide.
 29. The composition of claim 28 wherein the biocide is selected from the group consisting of 5-chloro-2-methyl-4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, glutaraldehyde, 2,2-dibromo-3-nitrilopropionamide, 2-bromo-2-nitropropane-1,3 diol, 1-bromo-1-(bromomethyl)-1,3-propanedicarbonitrile, tetrachloroisophthalonitrile, alkyldimethylbenzylammonium chloride, dimethyl dialkyl ammonium chloride, poly(oxyethylene(dimethyliminio)ethylene(diemethyliminio)ethylene dichloride, methylene bisthiocyanate, 2-decylthioethanamine, tetrakishydroxymethyl phosphonium sulfate, dithiocarbamate, cyanodithioimidocarbonate, 2-methyl-5-nitroimidazole-1-ethanol, 2-(2-bromo-2-nitroethenyl)furan, beta-bromo-beta-nitrostyrene, beta-nitrostyrene, beta-nitrovinyl furan, 2-bromo-2-bromomethyl glutaronitrile, bis(trichloromethyl) sulfone, S-(2-hydroxypropyl)thiomethanesulfonate, tetrahydro-3,5-dimethyl-2H-1,3,5-hydrazine-2-thione, 2-(thiocyanomethylthio)benzothiazole, 2-bromo-4′-hydroxyacetophenone, 1,4-bis(bromoacetoxy)-2-butene, bis(tributyltin)oxide, copper sulfate, (2-tert-butylamino)-4-chloro-6-(ethylamino)-s-triazine, dodecylguanidine acetate, dodecylguanidine hydrochloride, coco alkyldimethylamine oxide, n-coco alkyltrimethylenediamine, tetra-alkyl phosphonium chloride, 7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylic acid, 2-(4-thiazolyl)-benzimidazole, orthophenylphenol, 6-ethoxy-1,2-dihydro-2,2,4-trimethyl quinoline and 4,5-dichloro-2-n-octyl-4-isothiazoline-3-one.
 30. The composition of claim 28 wherein the amount of hops extract is in the range of about 0.1% to about 99%, the amount of biocide is in the range of about 0.1% to about 99% and the amount of surfactant is in the range of about 0.1% to about 99%. 